Apparatus for evaporating liquids indirectly



Nov. 24, 1925 K. L. E. THUNHOLM {PPARATUS FOR EVAPORATING LIQUIDS INDIRECTLY Filed March 9, 1921` Patented Nov. Z4, 1925.

KARL LAR?, ESAIAS THUNHLM, Oli1 REBRG, SWEDEN.

A PEARA'JJUS FR EVAPORATING LIQUDS INDIRECTLY.

Application filed March 9, 1921.

To all 107mm t 072663/ concern.'

lie it lcnoivn that I, Kann LAas Esame lrrUNiioiiau a subject ot the Kingl of Sweden, residing at Vastragatan 2l, Orebro, in the Kingdom of Sweden, -rave invented certain new and useful improvement-s .in Apparatus for Evaporatingl Liquids indirectly, of which the following` is a specilicatiou.

This invention relates to apparatus 'tor evaporating liquids indirectly ot that type, in which the liquid during` the evaporating operation is spread on a surface and is heated by the transmission ot heat indirectly trom a heating medium, for instance saturated Water steam, acting on the opposite side of the said surface. ln apparatus ot the said type it is of importance that the heat transmitting surface is thin and ot a material ot great heat conductingl capacity, which is able to resist the corroding action, it any, of the liquid. Apparatus, hitherto used, have been objectionable in many respects tor the reason, that the heat transmitting surfaces have not been so arranged, that they are able in course ot time to resist the pressure in the steam channels and consequently are easily deformed. A further drawback of the said apparatus consists in the ivaterot condensation beingl deposited on the heat transmitting surfaces. Experience, however, has proved, that even the thinnest coat of Water on the heat transmitting` surface, for instance a thickness ot only 0.1 millimetre, is able to reduce the total amount of transmitted heat to one lia-lil' oit the heat, which ,is transn'iitted, it the sur tace is per- Vl'ectly :tree lrom water.

The object oit thisI invention is to improve the .aid apparatus in such manner, that the said inconveniences are removed. For tha purpose the ring-shaped heat transmitting members, which preferably are made oit cast iron, are provided With a number of concentric channels for the steam, Which channels have a ren'iovable, comparatively thin top Wall which constitutes the proper heat transmitting surface. The said top Wall is made of a material oi great heat conducting capacity and having great resistance against the liquid, which is evaporated. The heat transmitting,I members are so shaped, that the heat transmittinp,` surface is slightly concavo-convex, i. e. it forms a part ot a sphere with a long radius and thus has a certain initial tension, so that it is able, Without altering its shape, to resist the pressure ex- Seral No. 450,929.

isting in the steam channel. The depositing of Water of condensation on the heat transmitting surface is prevented by the providing ot a number ot ringshaped, concentric steam channels, the cross sectional area ot which is successively reduced from the channel, into which the steam is introduced, to the channel, from which the steam escapes, which consequently has the smallest cross sectional area. This results in the velocity ot the steam being, practically, the same in all channels. Each channel may be ot uniform breadth along its Whole length or successively contract from its inlet toward its outlet ends. The channel having the great est cross sectional area, in which channel the steam is lirst introduced, is preferably located nearest to the centre.

The water oit condensation deposited on the heat transmitting surface is then forced by the centrifugal torce away toward the vertical Walls ot the channels, so that the water flows down to the bottom ot the channel.

In the accompanying` drawing Fig. l is a vertical section on the line 1-1 ot Fig. 2 ot a portion ot' an apparatus arranged in accordance With this invention. Fig. 2 is a plan View, partially a horizontal section of the apparatus. Fig. 8 shows a detail.

The apparatus comprises a number oi ringshaped heating members 20, 20EL and 20" which are connected Wit-h one another by means ot bolts 2l 7 threaded into holes 22 in the lugs 28.

in the drawing the heating members have three concentric channels 3, Il and 5 for steam, but the number of the channels may, evidently, be varied. The said channels are separated trom one another by partitions 6 and 7 and their' top Wall consists of a thin, removable plate 11 oit a material of great heat conducting capacity, for instance copper. As seen from the drawing the said plate has a slightly concavo-conven shape, i. e. it forms a part ot a sphere with a long radius in order that it may be more adapted to sustain strainings due to expansion and that Water ot condensation, which possibly is deposited on the member, may run ott more easily. VThe said shape is gained by the top edges ot the intermediate walls 6 and 7 and of the outer Wall being located on levels decreasing in height toward the pe riphery.

l. is the steam inlet. The steam passes from the said inlet through the passage 2 into the inner steam channel 3. From the channel 3 the steam passes at the end S ot' the intermediate wall 6 into the channel 1+', and then at the end 9 o't` the intermediate wall 7 into the outer channel 5 and through the channel 5 and escapes through theoutlet 10.

In the form ot execution shown in the drawing each ot the ring-shaped heating members is provided with a ring having a `flange il which prevents the liquid trom running` oli'. .Each ring has two :inwardly extending projections 12 located diametrically oppositel to one another. One ot the said projections has a hole 123, which also extends through the member 1T, through which the liquid runs down to the next ringshaped heating member. T he holes l?) are located in a zigzag order, so that in the heating member located below the heating member shown in Fig. Q, the hole is provided in the diametrically opposite projection l2, as shown by a dotted line in Fig. '2 and in Yfull lines in Fig. 1. Fig. 3 illustra-tes the connection ot the bottom walls by screw bolts 21.

The cross sectional area ot the channels den creases proportionally to the condensation of the steam, in order that the velocity ot the steam may be substantially constant in all channels in spite of the reducing ot the volume resulting from the condensation. Thus, in the drawing the innermostchannel 3, into which the steam is introduced, is the broadest one, for the reason that the condensation here is greatest. The width ot the succeeding channels then successively decreases. The broadest channel may, however, be located at the periphery ot the apparatus. In the drawing the width. o't thc respective channels is, tor constructional reasons, unvariable along the whole channel. lt would be more suitable, however, it each channel were successively reduced from the inlet end lo the outlet end, but such arrangement would render the apparatus considerably more expensive and complicated. A satisfactory result is gained more cheaply by the shown arrangement ot -the channels.

1t a specially effective runningl all ot the water ot condensation is desired small, flanges l5 extending downward from the plate 1l may be provided, at least in the broad channels, in order that the water particles need not travel such a long way before their striking an obstacle. This is suitable especially at low steam pressures, in which case it is et importance that the reduction ot the steam pressure is as slight as possible. The bottom walls 1T ought to be slightly conical, so that the bottoms of the chann ,is respectively successively slope trom the channel. into which the steam is led in order that. the running oli' ot the water may he facilitated and that the changing olf the shape effected by the heat may take place in a certain direction.

1 claim:

l. An apparatus tor vaporizing liquids P comprising severa-l superposed annular heating elements having annular flanges at their outer edges forming an enclosing wall, cach clement being provided with a plurality ot shallow concentric substantially annular channels communicating with each other, a heat transmitting plate t'or each element covering the channels in that element and adapted to serve as a heating means between a heating vapor introduced into said channels and the liquid which rests on said plates, a conduit at the outer edges ot said elements for introducing a heating :fluid into said channels, and a second conduit at the outer edges of said elements for discharging said tluid trom the channels, the cross section ot' the channels decreasing in size from the lirst mentioned conduit to the se@v ond conduit for the purpose of maintaining a practically uniform velocity for the heating medium in all the channels.

2. An apparatus tor heat treating materials including superposed heating elements cletachably connected together, each et said' elements including an inner ring and an outer ring with an inclined floor extending trom the inner ring to the outer ring, ribs on said iioor forming communicating channels, heat transmitting plates arranged between the iirst mentioned heating plates and vforming covers tor said channels and lioors to sustain the material to be treated, a .conduit for introducing heating medium into said channels, and a second conduit for discharging the heating medium from the channels.

3. An apparatus for heat treating materials including superposed heating elements detachably connected together, each oil? said elements including an inner ring and an outer ring with an inclined annular vHoor cxtending Atrom one ring to the other, vertical ribs on said floor torming communicating shallow channels, heat transmitting plates arranged between the heating elements and forming covers tor said channels, a conduit vfor introducing a heating' medium into said channels, a second conduit 'for discharging the heating .medium trom the channels, an annular 'flange member arranged on the inner ring of each heating element and provided with bul'ged portions, certain of said bulged portions together with the inner rings being apertured to permit the mate` rial undergoing treatment to flow downwardly from one oi? the heat transmitting plates to another heat transmitting plate arranged below.

t. Au apparatus tor heat treating materials including superposed heating elements,

each eonsistinl of an annular substantially concave convexY Hoor provided at its inner edge with an inner ring` and provided at its outer edge with an upwardly extending,l (lange and with a downwardly extending annular flange, the upwardly extending flange or each heating' element beingl of less height. than the inner ring otf the element, substantially annular ribs projecting upwardly Vtrom each of said `floors and forming` substantially concentric shallow Channels, means tor introducing' a heating' medium into and diseliangingv the heating medium ,li-oui said Channels, heat transmitting plates arranged between the elements and havingl their inner edge portions resting on the inner rings and their outer edge portions aranged between the [langes of the elements, and annulaiflanged members restingl on said plates immediately in line with the inner rings and provided with means to permit the fluid being treated to flow oil of one heating plate downwardly on to the heatingl plate below.

In testimony whereof I have allixed my 25 signature.

KARL LABS ESAIAS THUNHOLM. 

